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Xi'an, China

Northwestern Polytechnical University is a National Key University, directed by the Ministry of Industry and Information Technology of the People's Republic of China, located in Xi'an, Shaanxi, China. The university emphasizes on the education and research in aeronautical, astronautical and marine engineering. In February 2012, NPU has 13,736 graduate students and 14,395 undergraduate students. Wikipedia.

Zhao X.,Northwestern Polytechnical University
Journal of Materials Chemistry | Year: 2012

The bottom-up fabrication of facile, lower-cost, larger areas optical metamaterials (OMMs) is expected to provide important benefits for applications in stealth technology and communication networks. Currently available OMMs at optical wavelengths are all composed of periodic structures, and fabricated by top-down approaches of e-beam lithography or focused ion beam technique. Limited by the high cost and extremely small sample volumes size, the fabrication of visible OMMs is still quite challenging on the nanometer scale. The rapid maturation of synthetic methodology in the field of the nanometer scale has lead to the creation of new materials at an incredible rate. In this review, we regard a V-shaped core as an artificial atom and a dendritic cell as an artificial molecule, and address the bottom-up fabrication and performance of optical metamaterials, and with an outlook toward developing devices capable of operating in optical media. © 2012 The Royal Society of Chemistry. Source

Deng Y.,Northwestern Polytechnical University
Applied Intelligence | Year: 2015

Dempster-Shafer evidence theory is an efficient tool in knowledge reasoning and decision-making under uncertain environments. Conflict management is an open issue in Dempster-Shafer evidence theory. In past decades, a large amount of research has been conducted on this issue. In this paper, we propose a new theory called generalized evidence theory (GET). In comparison with classical evidence theory, GET addresses conflict management in an open world, where the frame of discernment is incomplete because of uncertainty and incomplete knowledge. Within the presented GET, we define a novel concept called generalized basic probability assignment (GBPA) to model uncertain information, and provide a generalized combination rule (GCR) for the combination of GBPAs, and build a generalized conflict model to measure conflict among evidences. Conflicting evidence can be effectively handled using the GET framework. We present many numerical examples that demonstrate that the proposed GET can explain and deal with conflicting evidence more reasonably than existing methods. © 2015, Springer Science+Business Media New York. Source

Cao Z.,University of Delaware | Wei B.,Northwestern Polytechnical University | Wei B.,University of Delaware
Energy and Environmental Science | Year: 2013

The ever-increasing demand of electricity storage is a growing challenge among a broad range of renewable energy sources. The development of high-energy storage devices has been one of the most important research areas in modern days. In particular, rechargeable batteries and electrochemical capacitors are recognized as the primary power sources for applications from portable electronic devices to electric vehicles. In order to power the emerging flexible/stretchable electronics, power sources themselves must be able to accommodate high levels of deformation and stretchability in addition to high energy and power density, light weight, miniaturization in size, safety qualification, and other significant characteristics. Utilizing carbon nanotubes (CNTs) for various energy storage applications such as electrodes in lithium ion batteries and supercapacitors, are under close scrutiny because of the promising electrochemical performance in addition to their extraordinary tensile strength and flexibility, ultrahigh surface area, and excellent thermal and electrical conductivity. Recently, there has been growing interest in investigating CNT macro-films with large-scale organized nanostructures of desired shape and form and unique and enhanced properties: integrity and stability to realize the scaled-up energy storage devices. In this perspective, research efforts in assembling 2-D CNT macro-films using a chemical vapor deposition method and their applications for different energy storage devices including stretchable supercapacitors, supercapacitors working under extreme conditions such as high temperature and high pressure, and lithium-ion batteries are discussed. In details, this paper provides an original overview involving the effect of compressive stress on the electrochemical behavior of flexible supercapacitors assembled with CNT macro-film electrodes and electrolytes with different anions and cations; the demonstration of the dynamic and galvanic stability of stretchable supercapacitor using buckled CNT macro-films by an in situ dynamic electrochemical testing method; the understandings on the self-discharge mechanisms of CNT macrofilm-based supercapacitors from both electrode and electrolyte aspects; and the investigation of the electrochemical properties of the tandem structure of active materials (e.g. thin porous silicon film and CuO) with CNT macro-films acting as a flexible and adhesive layer between the active layers and current collectors for lithium-ion batteries. Future research on CNT macro-films-based lithium-sulfur batteries and lithium-air batteries is also discussed. © 2013 The Royal Society of Chemistry. Source

Liu H.,Northwestern Polytechnical University | Rodriguez R.M.,University of Jaen
Information Sciences | Year: 2014

Decision making is a process common to human beings. The uncertainty and fuzziness of problems demand the use of the fuzzy linguistic approach to model qualitative aspects of problems related to decision. The recent proposal of hesitant fuzzy linguistic term sets supports the elicitation of comparative linguistic expressions in hesitant situations when experts hesitate among different linguistic terms to provide their assessments. The use of linguistic intervals whose results lose their initial fuzzy representation was introduced to facilitate the computing processes in which such expressions are used. The aim of this paper is to present a new representation of the hesitant fuzzy linguistic term sets by means of a fuzzy envelope to carry out the computing with words processes. This new fuzzy envelope can be directly applied to fuzzy multicriteria decision making models. An illustrative example of its application to a supplier selection problem through the use of fuzzy TOPSIS is presented. © 2013 Elsevier Inc. All rights reserved. Source

Yang F.,Xidian University | Wan S.,Northwestern Polytechnical University
IEEE Communications Magazine | Year: 2012

Bitstream-based methods are intuitively suited for quality assessment of networked video services, and are currently under intense investigations in terms of research and standardization activities. This article examines the factors that may affect the quality of the networked video, and reviews the state-of-the-art techniques as well as standardization progress in bitstreambased video quality assessment. According to different levels of access to the bitstream, three types of models are described and compared: the parametric, packet layer, and bitstream-layer models. © 1979-2012 IEEE. Source

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